Electrical controller for an industrial truck



Oct-25, 1960 B. l. ULINsKl 2,957,536

ELECTRICAL CONTROLLER FOR AN INDUSTRIAL TRUCK Filed Mal'Gh 25, 1959 lnited States Patent' ELECTRICAL CQNTROLLER FOR AN INDUSTRIAL TRUCK Bronislaus I. Ulinski, Flossmoor, Ill., assigner to The Yale and Towne Manufacturing Company, Stamford,

Conn., a corporation of Connecticut Filed Mar. 25, 1959, Ser. No.'-801,953

'7 Claims. (Cl.'130-82) This invention relates to a controller Afor an industrial truck. Those skilled in the art willfully-appreciate that in an industrial truck there is usually employed a rotating controller shaft which, upon rotation, controls the closing of certain traction circuits. It is important, in controllers of the class indicated, that the controller shaft be returned to zero orneutral position in the event of injury to the operator of the truck. Heretofore, it has been customary to employ a treadle mechanically connected to the controller shaft so that when the operator is standing with one foot on the treadle, the controller shaft is readily adapted for manipulation. However, should the operator remove his foot from the treadle, as in the case of an accident, the controller shaft will be returned immediately to zero or neutral position so that the truck will be stopped.

Due to the fact that industrial trucks must occupy an extremely small space, it is extremely difficult to effect the operation of the controller in the manner I have described. Various means have been utilized to actuate the controller shaft, such as levers, rods, and other types of means. Arrangements of the particular class require considerable apparatus and mechanisms, and are subject to wear, so as to render them ineffective when an emergency arises.

Asa feature of my invention, the controller is actuated thro-ugh extremely simple means occupying very little room and fullyand effectively positive. Thus, as a feature of my invention, I utilize a controller shaft that is normally returned to zero or neutral position by a powerful positively operating spring, this `spring being preferably housed within the controller housing in which the shaft is rotated and in close juxtaposed relation to that shaft. I then arrange to applyiluid pressure to the very member that is actuated by the spring, whereby to press that member effectively in a direction opposed to that in which it is moved by the spring, this being accomplished by a very simple and effective fluid actuated piston that is itself preferably housed within the same housing in which the controller shaft is rotated.

As a further particular feature of the invention, I may take a conventional controller in .which the shaft is returned to neutral position by a spring plunger. Simply through the forming of a small cylinder Within the housing, mounting a piston within the housing of thecontroller, and securing this piston to the spring-actuated plunger, I make possible the maintenance of the spring-actuated plunger away from the .controller shaft whenever uid pressure is applied to the piston. It is extremely simple in a truck of the class described for the application of the fluid pressure only when the operator is pressing against a treadle or the like. Obviously, in the manner indicated, I am able to control a standard and simple type of controller through the lluid pressure of the fluid system found in practically all industrial trucks.

I have thus outlined rather broadly the more important features of -my invention in order that the detailed description thereof that follows may be better understood, and in order that my contribution to the art may "ece be better appreciated. There are, of course, additional features of my invention that will be described hereinafter and which will form the subject ofthe claims appended hereto. Thoseskilled in the art will appreciate that the conception on which my disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the Several purposes of my invention. It is important,-therefore, that the claims be regarded as including ysuch equivalent constructions as do not depart from the spirit and scope of my invention, in order to prevent the appropriation of my invention by those skilled in the art.

The invention having been broadly described, a more detailed description of one embodiment of the invention is given hereafter by reference to the accompanying drawings wherein:

Fig. l is a sectional view of one embodiment of the controller of the invention taken on theline 1-'-1. of Fig. 2, showing the spring means for returning the controller shaft to neutral position and the fluid actuated piston for rendering the spring means ineffective. Fig. yl also includes a diagram of the fluid control circuit;

Fig. 2 is a left end view of the controller as shown in Fig. l and Fig. 3 is a sectional view taken on line 3-3. of Fig. l showing the full length of the controller shaft and the electrical switches actuated by the rotation of .theshaft- Referring to the drawings, the controller shaft, generally designated by the reference numeral 10,.is supported for rotation in a housing 11 by means kof suitable ball bearings 12 carried adjacent each end of the housing 11.

In Figs. l and 3 the controller shaft 10 is shown in a neutral or zero position. The controller shaft is adapted to be rotated for slightly less than y in. each direction from the neutral position by. a suitable handle 13.

As best shown in Fig. 3, the controller is adapted to control the closing of a number of switches 14 which are secured to the housing 11 at spaced intervals. The switches 14 control varioustraction circuits of thetruck. The switches 1d are operatively connected to the controller shaft 1() by follower rods 15 which are slidably mounted in suitable bores in the housing 11. The inner ends of the follower rods 15 ride on the surface of the controller shaft 10 and move inwardly when they engage hat spots 16 provided on the shaft 10 as the shaft 10 is rotated to thereby permit the spring actuated switches 14 to open or close depending on whether they are normally closed or normally open switches.

Ball ldetents 17 actuated by springs 18 are carried in suitable bores 19 in the housing 11 and retained therein by threaded plugs Ztl. The plugs 26 also serve to adjust the spring pressure on theball detents 17. The ball detents are adapted to engage in circumferentially spaced recesses 21 provided in 'the surface'of the controller shaft 10 to thereby serve to holdtheshaftl in various rotated positions as determined by the operator.

The mechanism for returning the `controller .shaft itl to neutral position includes a plungerZl having an end 21a adapted to ht into a slot 22 formed in the controller shaft 10. The plunger 21 is forced in a direction to urge the end21a into the slot 22 by astrong compressed helical spring 23. The spring 23 surrounds the plunger 21 and bears at one end on shoulder 2lb Vwhich is integral ywith the plunger 21 and bears at the other end against the inner surface of the shoulder of a-bore 24 of a housing 25 which surrounds the spring 23. The'housing 25 is secured to the controller housing 11 by means of bolts 26.

Referring to Fig. l, it will be apparent that the end 21a being pressed by the spring 23 against the base of the slot 22 will hold the controller shaft in the neutral or zero position as shown'inFig. l, or will return the controller shaft to the neutral position if it is not in the neutral position.

In order to disengage the end 21a of the plunger 21 from the slot 22 so that the operator may rotate the controller shaft by a handle 13, there is provided, in accordance with the invention, a fluid pressure actuated piston 27 which is connected to the plunger 21 so that the plunger 21 may be retracted against the force of the compressed spring 23 by actuation of the piston 27. A cylinder for the piston 27 is conveniently provided by forming a bore 28 through the controller housing 1I and closing one end of the bore with a suitable plug 29. The piston 27 may be provided with suitable piston rings 30 and a suitable shaft seal 32 may be provided at the end of the bore 28. Outward movement of the piston 27 is transmitted to the plunger 21 by means of a coupling 33 which surrounds and is secured to the outer end of the plunger 21 by means of a bolt 34 which extends through the coupling and plunger 21, as best shown in Fig. 1. The outer end 27a of the piston 27 is received in an opening in an extension of the coupling 33.

In accordance with the invention, iiuid under pressure is admitted to the bore or cylinder 28 by a conduit 35 when a self-returning foot treadle valve 36 is depressed by the operator of the truck. Admission of fluid under pressure through the conduit 35 extends the end 27a of the piston 27 and retracts the plunger 21 which is attached thereto by the coupling 33. As the plunger 21 is retracted, the end 21a thereof is disengaged from the slot 22 and the controller shaft 10 may be then rotated by the operator. Thus, before the operator can rotate the controller shaft 10 to operate the truck, his foot must always be depressing the treadle valve 36. Should the operator remove his foot from the treadle valve 36, as might be the case in an accident, the uid under pressure on the piston 27 would be released and bypassed by the valve 36 through a conduit 37 to the reservoir. The compressed spring 23 would then return the plunger 21 to the position shown in Figs. l and 3, camming the controller shaft 10 to the neutral or zero position. Leakage past the piston 27 is returned to the reservoir through a conduit 38.

From the above description it can be seen that I have provided a very simple, compact, but efcient controller in which the controller shaft will be automatically returned to neutral or zero position should the operator remove his foot from the treadle valve for any reason. It will also be apparent that the simplicity of the invention permits conversion of conventional controllers to a controller of the type of the instant invention by simply forming a small cylinder within the conventional housing of the controller, providing a piston in the cylinder and securing the piston to a spring-actuated plunger or cam for returning the controller to a neutral position. The controller of the invention utilizes the uid system commonly found on trucks of the class described and eliminates the rods, levers, and other space-consuming mechanism heretofore used for a similar purpose.

While a preferred embodiment of the invention has been shown and described, it will be appreciated that changes and modifications may be made thereto without departing from the spirit and scope of the invention.

I now claim:

l. In a truck of the class described, a controller for a traction motor for said truck, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a source of uid pressure in said truck, an operator actuated treadle maintained in a downward position by the operator and movable upwardly when released by the operator, spring means urging said controller shaft to neutral position, a fluid pressure actuated piston mounted for reciprocation relative to said housing and adapted to render said spring means ineffective to return said controller shaft to neutral position when said piston is connected to said source of fluid pressure and is moved by said uid pressure in a particular direction relatively to said housing, and means whereby the upward movement of said treadle, when the operator steps oif the treadle, releases said uid pressure on said piston.

2. In a truck of the class described, a controller for a traction motor for said truck, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a source of uid pressure in said truck, an operator actuated treadle maintained in a downward position by the operator and movable upwardly When released by the operator, spring means urging said controller shaft to neutral position, a uid pressure actuated plunger mounted for reciprocation in a cylinder formed in said housing, said plunger rendering said spring means ineffective to return said controller shaft to neutral position when said cylinder is connected to said source of uid pressure and said plunger is moved in a particular direction relatively to said housing, and means whereby said treadle controls communication between said cylinder and said source of fluid pressure.

3. In a controller for a truck of the class described, a traction motor for said truck, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a source of fluid pressure in said truck, an operator actuated treadle maintained in a downward position by the operator and movable upwardly when released by the operator, spring means urging said controller shaft to neutral position, a fluid pressure actuated piston mounted for reciprocation relatively to said housing and adapted to render said spring means ineffective to return said controller shaft to neutral position when said piston is connected to said source of uid pressure and is moved by said fluid pressure in a particular direction relatively to said housing, and means whereby the upward movement of said treadle, as when the operator steps off the treadle, releases said fluid pressure on said piston.

4. In a controller for a truck of the class described, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a source of uid pressure in said truck, an operator actuated treadle maintained in a downward position by the operator and movable upwardly when released by the operator, a spring-pressed actuator urging said controller shaft to neutral position, a fluid pressure actuated piston mounted for reciprocation relatively to said housing and connected to said actuator, said piston rendering said springpressed actuator inoperative to return said controller shaft to neutral position when said piston is connected to said source of fluid pressure, and means whereby the upward movement of said treadle, as when the operator steps off the treadle, releases said fluid pressure on said piston.

5. In a truck of the olass described, a controller for a traction motor for said truck, a housing, a contro-ller shaft, means mounting said controller shaft for rotation 1n said housing, electric circuit controls actuated by rotation of said shaft, spring-actuated means for urging said controller shaft to a neutral position, a uid pressure actuated piston mounted for reciprocation relative to said housing, a source of fluid under pressure in said truck, a self-returning valve adapted to be depressed by the operator of the truck to admit fluid under pressure to move said piston in one direction, means inter-connecting said piston and said spring-actuated means to cause movement of said spring-actuated means to an ineffective position in response to the movement of said piston in said one direction. Y

6. In a truck of the class described, a controller for a traction motor for said truck, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a plunger mounted for movement towards and away from said shaft, spring means for urging an end of said plunger against a surface of said shaft to return and hold said shaft in a neutral position, a fluid-actuated piston mounted for reciprocation relative to said housing, a source of Huid under pressure in said truck, a self-returning treadle valve adapted to be depressed by the operator of the truck to admit uid under pressure to move said piston in one direction, means nterconnecting said plunger and said piston to disconnect said plunger from said shaft in response to movement of said piston in said one direction whereby said shaft may be rotated from said neutral position.

7. In a truck of the class described, a controller for a traction motor for said truck, a housing, a controller shaft, means mounting said controller shaft for rotation in said housing, electric circuit controls actuated by rotation of said shaft, a bore in said housing, a plunger mounted in said bore for movement toward and away from said shaft, spring means for urging one end of said plunger vagainst the surface of said shaft to return and hold said shaft in neutral position, a second bore in said housing, a fluid-actuated piston slidably mounted in said second bore, a source of uid pressure in said truck, a self-returning valve adapted to be depressed by the operator of the truck to admit fluid under pressure to move said piston in one direction, means inter-connecting said plunger and said piston to disconnect said plunger from said shaft in response to movement of said piston in said one direction whereby said shaft may be rotated from said neutral position.

References Cited in the file of this patent UNITED STATES PATENTS 1,719,678 Sweringen July 2, 1929 

